you have energy input. you have energy input. this task - the head can rotate this task - the head can rotate and slide away. and slide away. >> >> three, two, one, go. three, two, one, go. >> remember this >> remember this 100 g hit? 100 g hit? professor professor dumis has dumis has a 5-star a 5-star helmet reducing it bias much as helmet reducing it bias much as 50%, that's because the 50%, that's because the shell shell riskful. riskful. >> there are helmets that reduce >> there are helmets that reduce your risk. your risk. like 5-star cars reduce your like 5-star cars reduce your risk of dying in a car crash. risk of dying in a car crash. >> as for blake lawrence, the >> as for blake lawrence, the risks of the game that he had, risks of the game that he had, decision. decision. >> our head coach said, "your >> our head coach said, "your concussions are happening too concussions are happening too easily. easily. that summer, before my junior that summer, before my junior ner at nebraska, i told myself ner at nebraska, i told